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Rivet analyses reference

SND_2015_I1389908

Cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ between 1.05 and 2 GeV.
Experiment: SND (VEPP-2M)
Inspire ID: 1389908
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • J.Exp.Theor.Phys. 121 (2015) no.1, 27-34
Beams: e+ e-
Beam energies: (0.5, 0.5); (0.5, 0.5); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0) GeV
Run details:
  • e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ by SND for energies between 1.05 and 2 GeV. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Source code: SND_2015_I1389908.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief e+ e- > pi+ pi- pi0
 9  class SND_2015_I1389908 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(SND_2015_I1389908);
14
15
16    /// @name Analysis methods
17    /// @{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      // Initialise and register projections
22      declare(FinalState(), "FS");
23      book(_num3pi, 1,1,1);
24      for (const string& en : _num3pi.binning().edges<0>()) {
25        double end = std::stod(en)*GeV;
26        if(isCompatibleWithSqrtS(end)) {
27          _ecms = en;
28          break;
29        }
30      }
31      if(_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
32    }
33
34
35    /// Perform the per-event analysis
36    void analyze(const Event& event) {
37      const FinalState& fs = apply<FinalState>(event, "FS");
38
39      map<long,int> nCount;
40      int ntotal(0);
41      for (const Particle& p : fs.particles()) {
42	nCount[p.pid()] += 1;
43	++ntotal;
44      }
45      if(ntotal!=3) vetoEvent;
46      if(nCount[-211]==1&&nCount[211]==1&&nCount[111]==1)
47	_num3pi->fill(_ecms);
48    }
49
50
51    /// Normalise histograms etc., after the run
52    void finalize() {
53      scale(_num3pi, crossSection()/ sumOfWeights() /nanobarn);
54    }
55
56    /// @}
57
58
59    /// @name Histograms
60    /// @{
61    BinnedHistoPtr<string> _num3pi;
62    string _ecms;
63    /// @}
64
65
66  };
67
68
69  RIVET_DECLARE_PLUGIN(SND_2015_I1389908);
70
71
72}